1. Field of the Invention.
The present invention relates to agents for oxidative dyeing of keratin fibers, particularly human hair, based on a developer/coupler combination which contains an N-heteroarylmethyl-m-phenylenediamine derivative as the coupler, and to new N-heteroarylmethyl-m-phenylenediamine derivatives.
2. Description of the Related Art
In the area of keratin fiber dyeing, particularly hair dyeing, oxidation dyes have attained substantial importance. In this case, the coloration is produced by reaction of certain developers with certain couplers in the presence of an appropriate oxidant. Suitable developers are, in particular, 2,5-diaminotoluene, 2,5-diaminophenylethyl alcohol, p-aminophenol, 1,4-diaminobenzene and 4,5-diamino-1-(2-hydroxyethyl)-pyrazole, and suitable couplers are, for example, resorcinol, 2-methylresorcinol, 1-naphthol, 3-aminophenol, m-phenylenediamine, 2-amino-4-(2′-hydroxyethyl)amino-anisole, 1,3-diamino-4-(2′-hydroxyethoxy)benzene and 2,4-diamino-5-fluorotoluene.
The oxidation dyes used for dyeing human hair must meet numerous requirements in addition to that of being able to produce colorations of the desired intensity. For example, these dyes must be harmless from a toxicological and dermatological standpoint, and the hair colorations obtained must have good light fastness, resistance to permanent waving, acid fastness and rubbing fastness. In any case, however, in the absence of exposure to light, rubbing and chemicals, such colorations must remain stable over a period of at least 4 to 6 weeks. Moreover, by combining appropriate developers and couplers, it must be possible to create a wide range of different color shades.
Attempts have already been made to improve the properties of m-phenylenediamines by introduction of substituents. In this regard, the reader is referred to German Unexamined Patent Application DE 29 34 330 which, among other things, describes special N-substituted m-phenylenediamines as couplers. With the currently known dyeing agents, however, it is not possible to meet the requirements placed on dyeing agents in all respects.